Last of three parts Staff writer Forests are now at the forefront of climate-change debate in Japan.

Known as "carbon sinks" in the parlance of scientists, negotiators and global warming policy specialists, forests and other carbon dioxide-absorbing ecosystems are recognized as a means of offsetting greenhouse gas emissions.

The questions facing Japan on this score are: How much of a role can forests play in paring domestic emissions and how can Tokyo prove or validate this role?